What color to paint this office? It’s a north-facing room with one window that needs to be covered (right at entrance walkway). I can’t stand the terracotta color but at a loss for what else. Furniture is to be ordered so can go white, brown or black.

As many suggested to go with grey, I think you indeed should go with a little gray in your white. But very very subtle. So subtle that if you look at the color cards for white in first glance they all look alike, until you see one that’s slightly more grey!

But whatever color you put on the walls, it will never be cold looking thanks to the floor.
.. that’s if you don’t put heavy furniture in it. No oval office desk, but more a minimalistic style desk maybe without cabinets or with simple drawers right under the top. Light furniture that doesn’t block your view to the floor.